10.147 V$TRUE_CACHE_STAT

V$TRUE_CACHE_STAT displays information about True Cache metrics.

This view is populated only on a True Cache.

Column Datatype Description
MY_DGID NUMBER Data Guard hash ID for True Cache
REMOTE_DGID NUMBER Data Guard hash ID for the primary database
DEST_ID NUMBER

Log archive destination parameter identifier

The value of this column is always 0.

NAME VARCHAR2(32)

Name of the metric:

  • apply lag - Apply lag is a measure of the degree to which the data in True Cache lags behind the data in the primary database, due to delays in propagating and applying redo to True Cache.
  • list of blocks fetch latency - The average latency of True Cache while fetching blocks from the primary database in list of blocks fetch mode.
  • multiblock fetch latency - The average latency of True Cache while fetching blocks from the primary database in multiblock fetch mode.
  • prewarm progress - The current progress of True Cache prewarming its own buffer cache by proactively fetching the list of blocks remembered from the last warmed up state, that is, from the previous instance lifetime.
  • single block fetch latency - The average latency of True Cache while fetching blocks from the primary database in single block fetch mode.
  • transport lag - Transport lag is a measure of the degree to which the transport of redo to True Cache lags behind the generation of redo on the primary database. If there are one or more redo gaps on True Cache, the transport lag is calculated as if no redo has been received after the beginning of the earliest redo gap.

Note: The apply finish time and estimated startup time metrics are not meaningful on a True Cache and can be ignored.

VALUE VARCHAR2(64) Value of the metric
UNIT VARCHAR2(32) Unit of measurement
TIME_COMPUTED VARCHAR2(32) Local time on True Cache when the metric was computed
DATA_TIME VARCHAR2(32)

Local time on True Cache when the data used to compute the metric was received

The apply lag and transport lag metrics are computed based on data that is periodically received from the primary database. An unchanging value in this column across multiple queries indicates that True Cache is not receiving data from the primary database.

CON_ID NUMBER

The ID of the container to which the data pertains.

The value of this column is always 0 (CDB$ROOT container).

Note:

This view is available starting with Oracle Database 23ai.